He was a Norwegian swimmer. He represented the clubs Vestkantsvømmerne (1995-2010) and Bærumssvømmerne (2011-2012). Dale Oen's gold at the 2008 European Championships made him the first Norwegian male to win a medal at a major international long course championship. Dale Oen won the 100m breaststroke at the World Championships in Shanghai last July, three years after claiming Olympic silver in Beijing.
He was one of Norway's top hopes for success at this summer's Olympic Games in London.